Tim: "I wanna hook up with Kim, but Stacy's my girlfriend"
John: "I don't understand...those are exclusively mutual aren't they?"
Tim: "Whaaa..?"
John: "If you break up with Stacy, Kim will be pissed cuz they're good friends. a.k.a. no Kim for you. On the other hand, if you don't hook up with Kim, Stacy will get bored of your drama-lacking relationship and eventually dump you. And then Kim will think you're a loser, and again no Kim for you.
Tim: You are a genius. I'll be right back